模糊UIImage以实现类似密码模糊壁纸的效果

Question

我想达到密码视图的效果（壁纸图片模糊且较暗）

这给了我一个黑屏

func blurWithCoreImage(){
    var inputImage = CIImage(image: UIImage(named: "wallpaper"));
    // Apply gaussian blur filter with radius of 30
    var gaussianBlurFilter = CIFilter(name: "CIGaussianBlur");
    gaussianBlurFilter.setValue(inputImage, forKey: "inputImage")
    gaussianBlurFilter.setValue(30, forKey: "inputRadius")
    var context  =  CIContext(options:nil)
    var cgImage = context.createCGImage(gaussianBlurFilter.outputImage, fromRect: inputImage.extent())
    // Set up output context.
    UIGraphicsBeginImageContext(self.view.frame.size);
    var outputContext = UIGraphicsGetCurrentContext();
    // Invert image coordinates
    CGContextScaleCTM(outputContext, 1.0, -1.0);
    CGContextTranslateCTM(outputContext, 0, -self.view.frame.size.height);
    // Draw base image.
    CGContextDrawImage(outputContext, self.view.frame, cgImage);
    // Apply white tint
    CGContextSaveGState(outputContext);
    //  CGContextSetFillColorWithColor(outputContext, UIColor.blackColor().CGColor!);
    CGContextFillRect(outputContext, self.view.frame);
    CGContextRestoreGState(outputContext);
    // Output image is ready.
    var outputImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    backgroundImg.image =  outputImage;
}

此功能会使图像模糊，但会使图像缩小，并且在密码视图中效果太差

func blurWithCoreImage2(){
    var ciimage = CIImage(image: UIImage(named: "passcode"))
    var filter = CIFilter(name:"CIGaussianBlur")
    filter.setDefaults()
    filter.setValue(ciimage, forKey: kCIInputImageKey)
    filter.setValue(1, forKey: kCIInputRadiusKey)
    var outputImage = filter.outputImage;
    var finalImage = UIImage(CIImage: outputImage);
    backgroundImg.image =  finalImage;
    UIGraphicsEndImageContext();
}

Answer 1

由于您只需要支持iOS 8及以上版本，因此可以使用新的UIVisualEffectView，这是添加模糊的新内置方式。

它非常容易使用，如下所示：

let blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Dark)
let blurView = UIVisualEffectView(effect: blurEffect)
blurView.frame = myFrame
self.view.addSubview(blurView)

您可以看到，您可以指定一个UIBlurEffectStyle，这将允许您使其更暗。

Answer 2

尝试模糊和裁剪图像

func applyBlurEffect(image: UIImage){
var imageToBlur = CIImage(image: image)
var blurfilter = CIFilter(name: "CIGaussianBlur")
blurfilter.setValue(5, forKey: kCIInputRadiusKey)
blurfilter.setValue(imageToBlur, forKey: "inputImage")
var resultImage = blurfilter.valueForKey("outputImage") as! CIImage
var blurredImage = UIImage(CIImage: resultImage)
var cropped:CIImage=resultImage.imageByCroppingToRect(CGRectMake(0, 0,imageToBlur.extent().size.width, imageToBlur.extent().size.height))
blurredImage = UIImage(CIImage: cropped)
self.backgroundImage.image = blurredImage
}

Answer 3

我试图更新答案，但被荒谬地拒绝了。以下是最新的语法：

Swift 3.1

let blurEffect = UIBlurEffect(style: .dark)
let blurView = UIVisualEffectView(effect: blurEffect)
self.view.addSubview(blurView)